Certified Ethical Hacker (CEH) Study Guide

Chapter 4. Sniffing and Evasion

I used to work in an office building just up the road. My office sat at the corner of two hallways that dead-ended just outside my door, with the door to the stairwell about five feet beyond. There was a large window at the end of the hallway looking out over the giant parking lot, with two big palm trees eternally swaying in the breeze just to the left. People would walk down to the end of the hallway and look out the window for a while, longing for freedom during the middle of a harsh workday. They often went down there to take or place personal calls on their cell phones. I know I was educated in Alabama, but I just assumed everyone knew: sound travels.

These people talked to their girlfriends, boyfriends, and, on a couple of occasions, the “other woman.” They called up banks and talked about their accounts or loans. They called businesses they’d applied to, trying to work out interview times and other issues. And all of this they did without any knowledge that someone was listening to all their conversations. Luckily for all these folks, I’m not an evil little guy. If I were, I would have been drawing from several bank accounts other than my own. I could also have set up and run a very successful dating agency—or a source for divorce proceedings.

In much the same way, people have conversations over networks all the time, without having any idea someone else could be listening in. In this chapter, I’m going to discuss ways for you to sit in the ...